1. Field of the Invention
This invention relates to heat-shrinkable articles comprising laminar electrical heaters.
2. Introduction to the Invention
Laminar electrical heaters, including those which comprise a laminar resistive heating element composed of a conductive polymer, are known. Some of these heaters comprise a pair of laminar electrodes, e.g. of metal foil or pierced metal sheet, with the heating element sandwiched between them. The heating element preferably exhibits PTC behavior, thus rendering the heater self-regulating. It is also known to make such heaters which are heat-recoverable or which are deformable so that they can be attached to heat-recoverable articles and will not prevent heat-recovery thereof. Reference may be made for example to U.S. Pat. Nos. 4,085,286, 4,177,376, 4,177,446, 4,223,209, and 4,318,220, and copending and commonly assigned patent application Ser. Nos. 818,711 and 254,352, published as European Applicaion No. 63,440, and the copending and commonly assigned patent application filed on May 11, 1983 by Chazan et al Ser. No. 493,445. For further details concerning conductive polymers and electrical devices concerning them, reference may be made to U.S. Pat. Nos. 2,952,761, 2,978,665, 3,243,753, 3,351,882, 3,571,777, 3,757,086, 3,793,716, 3,823,217, 3,858,144, 3,861,029, 4,017,715, 4,072,848, 4,117,312, 4,177,446, 4,188,276, 4,237,441, 4,242,573, 4,246,468, 4,250,400, 4,255,698, 4,271,350, 4,272,471, 4,304,987, 4,309,596, 4,309,597, 4,314,230, 4,315,237, 4,317,027, 4,318,881 and 4,330,704; J. Applied Polymer Science 19, 813-815 (1975), Klason and Kubat; Polymer Engineering and Science 18, 649-653 (1978), Narkis et al; and commonly assigned U.S. Ser. Nos. 601,424 (Moyer), now abandoned, published as German OLS No. 2,634,999; 750,149 (Kamath et al.) now abandoned, published as German OLS No. 2,755,077; 732,792 (Van Konynenburg et al), now abandoned, published as German OLS No. 2,746,602; 798,154 (Horsma et al), now abandoned, published as German OLS No. 2,821,799; 134,354 (Lutz); 141,984 (Gotcher et al.), published as European Application No. 38718; 141,987 (Middleman et al.), published as European Application No. 38715, 141,988 (Fouts et al.), also published as European Application No. 38718, 141,989 (Evans), published as European Application No. 38713, 141,991 (Fouts et al.), published as European Application No. 38714, 142,053 (Middleman et al.), published as European Application No. 38716, 150,909 (Sopory) and 150,910 (Sopory), published as UK Application No. 2076106 A, 184,647 (Lutz), 250,491 (Jacobs et al.) 273,525 (Walty), 274,010 (Walty et al.), 272,854 (Stewart et al.), 300,709 (van Konynenburg et al.), 369,309 (Midgley et al.), 380,400 (Kamath) and 418,354 (Gurevich). The disclosure of each of the patents, publications and applications referred to above is incorporated herein by reference.